12v 5ah to 5v 200ma power supply

[prafful]

hello,

I want to built power supply 5V dc to run mcu(max 200ma current).

as a input i want to give the supply from my bike's battery 12V 5AH.

i dont know how to convert DC to DC.

thanks in advance..

 

[jasonc2]

A TL2575-5 regulator plus a handful of passive parts will do most of the work for you for just a couple dollars:

Product: https://www.mouser.com/ProductDetai...nLMdcWnKADpS18QNhhNNwdOKVZyOVFQgaB9Y%2bug4dE=
Datasheet: **broken link removed**

The circuit you can use is on the bottom of page 3 of the datasheet.

J

P.S. DIP package if you prefer (https://www.mouser.com/ProductDetai...=odmYgEirbww5cPXHatWL7bC3Gemd4uZ8ZXJfqw/DysY=) but not as efficient at dispersing heat.

 

[rfredel]

Hello prafful,

here I show you an other circuit, what is easier then that of jasonc2.



This circuit use a linear regulator with a max. current of 1A. So you can change the fuse and take more current.

Regards

Rainer

 

[crutschow]

Be aware that the regulator will dissipate power which require a small heat-sink. For 200mA @ 5V output, the dissipation when the bike is charging the battery would be about 1.9W maximum. It increases if you draw higher output current, of course.

 

[tpetar]

Use 7805 1A or 78S05 2A voltage regulator. Its simplest and cheapest way, if we exlude zener diode.

You can solder regulator on PCB in horizontal position like smd component, instead of usage regular heatsink.

 

[rfredel]

Hello crutschow,

you are right, that a small heat sink is necessary. I only want to show, that it is possible to make it without a switch mode circuit.

Please give me a advise, if I must tell, when heat sink or other accessories are necessery. You are an older Member then I. :grin:

Regards

Rainer

 

[prafful]

thanks to all of you...

but i m still afraid that 7805 can make 5A to 200mA???

is it ok if I give 12V and 5A supply directly to 7805..???

 

[crutschow]

you are right, that a small heat sink is necessary. I only want to show, that it is possible to make it without a switch mode circuit.

Please give me a advise, if I must tell, when heat sink or other accessories are necessery. You are an older Member then I. :

For 1.9W a small clip-on heat finned heat-sink (with perhaps a 15-20W/C thermal resistance or better) to a TO-220 regulator package should be sufficient.

I'm not that old. ;-)

 

[rfredel]

Hello prafful,

the 7805 has intern current limiting to 1A. The 5Ah of your battery is their capacity. It means, that your battery can deliver 5 A for one hour or 1A for 5 hours. In your case, with 200 mA, you can use your battery for 25 hours before your must charge the battery.

Regards

Rainer

 

[tpetar]

thanks to all of you...

but i m still afraid that 7805 can make 5A to 200mA???

is it ok if I give 12V and 5A supply directly to 7805..???

:shock: Is this some joke ?

What 5A from 7805 ?

7805 max current is 1A
78S05 max current is 2A
78T05 max current is 3A

All three variant can supply current what you need, you say 200mA.

Battery have 5Ah! Dont mix battery capacity with amperage in circuit, and you dont need 5A you need 200mA did you forgot.

5Ah is not 5A !

s it ok if I give 12V and 5A supply directly to 7805..???

How do you mean You give 5A ?

Battery of 5Ah (this is not 5A) have capacity of 5Ah, and you can drain from that battery lower current, like 10mA, 100mA 500mA 1A or any other amperage. Current what you will have in your designed circuit will be linked with total resistance and impendance in your circuit depending on parts what you used. Amount of energy is limited to battery 5Ah capacity in 10h or 20h discharge time. If you drain on example 1A or 2A you will dont have and cannot expect 5Ah, then you will get much much lower amount of power.

Look Ohm Law.

This is voltage regulator and this part regulate voltage not current. You say in first post that you need 5V 200mA from 12V 5Ah battery.

I think that elementary knowledge is needed before someone start to do something.

I hope that bike have small fire extinguisher for any case.

Maybe is better to consult and hire someone to make it for you.

;-)

 

[jasonc2]

Or you could just spend $6.90 on a power supply board designed specifically for this purpose and not waste any more time :

https://www.futurlec.com/Mini_Power.shtml

7-12V in (same dropout as the 7805), 5V 1A max out. Incidentally it uses the TL2575-5 as well (and yes it has a power LED ). It's 4.5cm x 5.5cm so if that's small enough then I say go for it.

Anyways: The TL2575-5 can handle it and the circuit has the same component count as rfredel's above. The LM7805 can also handle up to 35V input and up to 2.2A output. It has a slightly wider output voltage tolerance than the TL2575 (4.8 - 5.2 as opposed to 4.9 - 5.1 according to datasheet) but that may work for you. The switching regulator is more efficient and produces less heat than the linear one, you may not need a heat sink.

Also, you aren't "giving" 5A to the regulator, you are providing a 12V (max) potential difference and it's drawing the current it needs.

 

[tpetar]

Hello prafful,

the 7805 has intern current limiting to 1A. The 5Ah of your battery is their capacity. It means, that your battery can deliver 5 A for one hour or 1A for 5 hours. In your case, with 200 mA, you can use your battery for 25 hours before your must charge the battery.

Regards

Rainer

Just one correction that battery cant give 5A for 1h. Capacity is calculated by 10h or 20h time of discharging that means 500mA in 10h discharging in best case. Battery datasheet given by manufacturer shows that in any case. Battery is chemical factory, she produce power when you put it in some circuit, and every factory have their production capacity per time.

Also Lead Acid batteries (starter, deep cycle are different story) are not designet to discharge them completely, for 30% ok (70% capacity remain full). Its float charge and this type should be always charged and full, just with small voltage oscilations in usage "floating voltage". Sulfatisation will occur if they rest discharged, and they must be immidietly charged when discharge occur.


Peukert Law
http://en.wikipedia.org/wiki/Peukert's_law
http://www.39pw.us/car/peukertEffect.html


Fast tutorial
http://www.vonwentzel.net/Battery/00.Glossary/


----------------------------


One more thing when switching voltage regulator is used, filtering should be carefully designed for ripple voltage, specially if uC is used in project.

Price of switching regulator can be almost like price of uC. :wink: But 7805 is very cheap and dissipate low power in this scenario

12V-5V=7V*0,2A=1,4W its :smile:

You can use even 78M05 its SMD up to 0,5A max current.

But its needed to get some elementary knowledge or hire some friend with knowledge to do this for you.


:wink:


Prafful what bike you have ?

Do You trying to make RPM for bike ?

 

[jasonc2]

One more thing when switching voltage regulator is used, filtering should be carefully designed for ripple voltage, specially if uC is used in project.

The TL2575 has ripple filter component values suggested, as long as you mind the current ratings.

Price of switching regulator can be almost like price of uC. :wink: But 7805 is very cheap and dissipate low power. 12V-5V=7V*0,2A=1,4W its :smile:

The suggested Futuretec board is $6.90, but it includes all components, already assembled on an appropriately traced PCB.

The 7805 is $0.70 + a $0.30 heat sink. The 2575 is $1.80.

But its its needed to get some elementary knowledge or hire some friend with knowledge to do this for you.

Which is a great case for a pre-assembled board.

Another option is to just grab an Arduino. It's much pricier @ ~$25.00, but takes 12V in, has everything already assembled (power supply to microcontroller), is loaded with inputs and outputs, and super easy to program (use their software through a USB port), so the extra price could easily be justified with less frustration and wheel reinventing, unless the goal is to learn how to build these things from scratch.

 

[tpetar]

Price of 7805 in my country is around 25din its around 0,25eur heatsink is :smile:

You need at least two capacitors in 7805 design and all of this is under 1eur.

That board $6,9 is to much expensive. This can be maded for around max 1eur or 1,22USD (1eur=1,22USD).

2575 switching regulator in my country have price about 2eur, on that should be added costs of other parts needed for 2575 circuit.

I use tons of 7805 and others regulators in projects, and never use universal regulator device. I make complete projects, without need of other external parts and needs, only in some cases uses wall adapters. Circuit should have yours internal regulation of voltage and current if needed.

Prafful should know that in bike charging system is some ripple to, and good filtering is needed if he whant to use some fine electronics including uC. I cant imagine what problems will showup in uC part of circuit, when there is problems in ordinary each day using 5V regulation section. :-?

Sorry my friend I dont respect Arduino, Pinguino, and that stuff like for some final device or circuit. This is just like toy or development devices/platform, something like lego bricks. With arduino can be made lots of things, but price, dimensions of Arduino,... this is not for usage in final project. Arduino cant be considered like pro or finalized project by my eyes, its like development board. Maybe they start to put arduino into cornflex boxes or detergent powder boxes. I saw lots of serious projects with arduino but size and price.... I think its better have direct solution on easier way, more compact, and of course cheaper, and Arduino we will put under christmas tree for kids or students in first year. Its just my thinking and look on Arduino of course.

:wink:


Circuit of 2575-5 :

Circuit with 7805 :

**broken link removed**


Mounting 78M05 SMD case up to 0,5A

**broken link removed**




Arduino lego castle or tower :

In left bottom corner you can see just ordinary every day 7805 TO-220 regulator.

**broken link removed**


General info about Arduino development platform :

http://en.wikipedia.org/wiki/Arduino

 

[jasonc2]

Maybe they start to put arduino into cornflex boxes or detergent powder boxes.

Ha! I would eat a lot more corn flakes then. :grin: (Then again, I'm a programmer by trade, not an ee -- most of my "professional" hardware is a couple breadboards and terminal blocks nailed to a piece of plywood).

 

[tpetar]

Ha! I would eat a lot more corn flakes then. :grin: (Then again, I'm a programmer by trade, not an ee -- most of my "professional" hardware is a couple breadboards and terminal blocks nailed to a piece of plywood).

Just good pay attention when you eat flakes, maybe they put in DIY variant disassembled like Kinder Egg with toy inside. Microcontroller pins can be nasty. :grin:

Of course EDABoard is good place to exchange different reviews and ideas. ;-)

 

[prafful]

Prafful what bike you have ?

Do You trying to make RPM for bike ?

hi.. I hsve YAMAHA SS125 ... I m making speedometet for it..
Using atmegs16a and reed switch... In bascom avr

 

[tpetar]

Buy my thinking You can safely include 7805 in your circuit, with at least two capacitors and small heat sink or use PCB as heatsink.

 

[cavnex]

Whoa, folks - the question is about a battery as the source.

Using a Regulator to get his output is incredibly inefficient. Yes, it's the easiest to design and use, but his battery isn't going to last very long. (And for the record, the current draw by the regulator won't be '200mA'; yikes. That's his desired draw at the output. The draw isn't even a simple Power (VI) calculation, either.)

The suggestion of a DC-DC converter was the best. There are many on the market, and they are much more efficient than a regulator.

(Translated: Use a regulator, his battery won't last long. Use a DC-DC converter, it'll last much longer.)

- - - Updated - - -

Whoa, folks - the question is about a battery as the source.

Using a Regulator to get his output is incredibly inefficient. Yes, it's the easiest to design and use, but his battery isn't going to last very long. (And for the record, the current draw by the regulator won't be '200mA'; yikes. That's his desired draw at the output. The draw isn't even a simple Power (VI) calculation, either.)

The suggestion of a DC-DC converter was the best. There are many on the market, and they are much more efficient than a regulator.

(Translated: Use a regulator, his battery won't last long. Use a DC-DC converter, it'll last much longer.)

 

[tpetar]

Whoa, folks - the question is about a battery as the source.

Using a Regulator to get his output is incredibly inefficient. Yes, it's the easiest to design and use, but his battery isn't going to last very long. (And for the record, the current draw by the regulator won't be '200mA'; yikes. That's his desired draw at the output. The draw isn't even a simple Power (VI) calculation, either.)

The suggestion of a DC-DC converter was the best. There are many on the market, and they are much more efficient than a regulator.

(Translated: Use a regulator, his battery won't last long. Use a DC-DC converter, it'll last much longer.)

I dissagree with you completely, maybe you should give us some concrete argument and solution.

You didnt give us nothing exactly concrete.

Give us calculation for "battery isn't going to last very long".

But its nice to see different thinking.

:wink:

- - - Updated - - -

Dont understand me wrong, I dont have anything wrong with switching regulators, I often use them.

But in this case for 200mA we should get some arguments. Did we read 2575 datasheet about minimal current, what if his circuit needs 100mA or 150mA - under 200mA.

We didnt hear prafful recently, what is his needs, smaller, cheaper, easier,.... maybe he use Arduino I dont know.

I think that we give to much time to this elementary thing, prafful should make cut and maybe try both solutions why not.

Its time to see situation in other threads.

I hope that will prafful make sucessfully his device, and use it on his bike.

:wink: